1. Technical Field
The present invention relates to a cover unit that accomplishes a cover opening operation lifting an access cover open from a closed position as a result of operating a lever disposed on one widthwise side of the access cover, one end of which is supported freely pivotably on the case of a printer, and relates to a printer having this cover unit.
2. Related Art
In order to load roll paper into the internal roll paper compartment of a thermal printer or other type of roll paper printer, an opening through which the roll paper can be inserted and removed is formed in the printer case. A cover unit that opens and closes the opening to the roll paper compartment is disposed with one end of an access cover supported freely pivotably on an edge of this opening so that the access cover can swing open and closed pivoting on this end.
Japanese Unexamined Patent Appl. Pub. JP-A-2004-276521 teaches such a thermal printer. The thermal printer taught in JP-A-2004-276521 has a printer cover (access cover) carrying a platen attached to the top of the case. The end of this printer cover at the back of the printer is supported on the printer frame by an intervening rotating support member. A lever disposed in the top of the printer cover is operated to lift and open the printer cover. This lever is formed on one end of an arm that is supported freely pivotably on a pivot point disposed at a front end part of the printer cover. When the lever is operated, the arm pivots and the printer cover lock is released, and a cover lift (a push-up unit) formed on the other end of the arm contacts a cover lift base formed on the printer case. When the arm rotates pivoting on the point of contact with this cover lift base, the printer cover that supports the arm is pushed up. The printer cover can then be manually raised and opened wide.
The configuration taught in JP-A-2004-276521 has the lever disposed on one side of the width of the printer cover, and an arm disposed on both sides of the width of the printer cover. As a result, operation of the lever (the pivoting operation) is transmitted to each of the arms through a rotation transfer member that extends widthwise to the printer cover, and the arms are configured to rotate together in response to operation of the lever.
When the printer cover is pushed up, the load of the weight from the printer cover side acts on the rotation transfer member that transmits the rotation of the lever to the arms. With this configuration, when the lever disposed to one end part of the rotation transfer member is operated, the load (weight) from the printer cover side causes the rotation transfer member to deform as a result of twisting or deflection, and the rotational positions of the arm on the side near the lever and the arm on the side far from the lever differ. As a result, both sides of the width of the printer cover do not start being pushed up at the same time, and the side closest to the lever begins being pushed up first. The printer cover and lever therefore twist or bend when being pushed up, and opening the printer cover smoothly becomes difficult.